The long-term goal of this research program is to develop and test brain tumor vaccines formed by electrofusion of dendritic cells (DC) and brain tumor stem cells (BTSC). BTSC contain somatically acquired clonal cytogenetic changes that are preserved in the more differentiated progeny that constitutes the bulk of the tumor. BTSC are high priority therapeutic targets because they have the capacity for;migration, exit and re-entry into cycle, self-renewal, and reconstitution of tumors. T cell immunotherapy is a promising adjuvant therapy for malignant brain tumors because the immune response is exquisitely specific for targeted antigens and is highly anatomically focused. Established intracranial tumors can be cured through systemic adoptive transfer of in vitro activated, tumor-sensitized T cells or through intrasplenic vaccination with DC- tumor fusion cells and adjuvant. In preliminary experiments electrofusion heterochimeras have been generated from several human glioblastoma stem cell lines and human DC. We propose to perform preclinical characterization of the biologic and immunologic properties of DC-BTSC fusion cells in order to establish their suitability for subsequent clinical testing. Brain tumor samples will be established in culture and conditions that selectively permit tumor stem cell growth will be investigated and optimized. Preservation of genetic abnormalities between the BTSC lines and the original tumor will be confirmed, as will expression of progenitor cell markers. Generation of electrofusion heterochimeras between human DC and BTSC will be performed and the cellular components and physical parameters that control fusion will be optimized. The pathologic and therapeutic responses to semi-xenogeneic fusion vaccines consisting of murine DC-human BTSC chimeras will be investigated using mice bearing progressive intracranial human BTSC tumors. These studies will explore whether the anti-tumor immune response is cross-reactive with normal brain progenitor cells and whether BTSC are effectively targeted. T cells from normal humans or GBM patients will be sensitized in vitro with DC-BTSC fusion cells and their reactivity against neural stem cells, various BTSC lines and autologous tumor will be analyzed. Patterns of immunologic cross-reactivity will be determined to explore whether common antigens can be targeted with a limited number of well-characterized BTSC lines with the goal of developing a standardized glioma vaccine.